pre-treatment of feedstock for enhanced biogas...

Günther Bochmann – IFA-Tulln

Pre-treatment of feedstock for enhanced

biogas production

Günther Bochmann

Lucy Montgomery


IEA Task 37

Work programme 2013-2015

Work

Knowledge exchange

Technical brochures

Success stories

Studies

Australia, Austria, Brazil, Denmark, European Commission, Finland,

France, Germany, Ireland, Norway, South Korea, Sweden,

Switzerland, The Netherlands, United Kingdom

www.iea-biogas.net2


Task 37

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Recently published brochures

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Aim of pretreatment technologies

Reduction of specific production costs

Substrate costs (%)

Investment costs (%)

Operation costs (%)

Realisation by

Increasing the biogas yield

Inceasing degradation rate

Increasing the plant efficiency

Reduction of operation costs

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Substrates

Kohlenhydrate

Proteine

Fette

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Carbon hydrates

Starch

Cellulose

Hemicellulose

Lignin

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OHHOCH2

O

CH3O

HOCH2

C CH2OH

O

O

HOCH2

CH3O O

OCH3

OH

CH2OHO

OCH3

O

O

O

CH3O

O

HOCH2

O

OCH3

OH

O

O

CH2OH

O

H2C

OH

O(C5H10O6)nH

CH2OHO

OCH3

O

OCH3CHO-CH=CH

CH2OH

O

OCH3

OCH3

O

CH3O

O

O

CH3

OCH3

OH

CH2

O


Impact pre-treatment

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Impact pretreatment on AD

Higher gas production can occur

HRT

Specific retention time in digester

Digester system need to be included

Viscosity

Substrate charateristics

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2

C

BGP A

BGP B


Pre-treatment technologies

Physical Mechanical Thermal Ultra sound Electrocinetical

Desintegration

Chemical Alcaline Acidic

Biological Microbiological Enzymatical

Combined

processes

Steam Explosion Extrusion Thermo-chemical

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Mechanical

Principle

Mechanical crushing

e.g. cutterbars

Advantage

Relatively low invesment costs

Relatively low energy demand

Disadvantage

Interfering materials reduce life

time of unit significantly

Mode of action

Increasing of specific surfaceQuelle: IKTS Frauenhofer

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Thermal

Principle

Thermal pretreatment leads to

disintegration of hard degradable

substances

Advantage

Higher gas yield

Exclusively heat demand

Disadvantage

High investment costs

Production of inhibiting substances

Mode of action

Solving of hemicellulose and swelling of

biomassQuelle: Dr. Franke ATZ/D

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Thermal processes

Non-enzymatic browning reaction

Maillard reaction

3 step process

End products melanoidines

N-catalysed process

pH-value essential for pathway

Bacteriostatic effect of intermediate products

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Steam explosion

Principle

Heating and abrupt decompression

Advantage

Higher gas yield

Only thermal energy

Disadvantage

Higher investment costs

Formation of inhibiting substances

Mode of action

Rupture cell structuresQuelle: Boku

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Thermo-mechanical

Principle

Extruders crush biomass

Advantage

Degradation rate

Relatively low investment costs

Low energy demand

Disadvantage

Interfering materials reduce life

time of unit significantly

Mode of action

Increasing of specific surface

Quelle: IFA Tulln

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Chemical

Principle

Addition of lye or acid in an additional pre-

treatment step

Advantage

Higher gas yield

Faster degradation

Disadvantage

Operation costs

Production of inhibiting products

Mode of action

Solving of lignocellulose complex

Quelle: enbasys

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Thermo-chemical

Principle

Support of chemicals through heat

Advantage

Higher gas yield

Faster degradation

Disadvantage

Operation costs

Production of inhibiting products

Mode of action

Solving of lignocellulose complex0

100

200

300

400

500

600

700

800

900

1000

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43

Bio

ga

sa

us

be

ute

[m

³/k

g o

TS

]

Zeit [d]

Ohne Behandlung

Thermochemischer Aufschluss 1

Thermochemischer Aufschluss 2

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Microbiological

Principle

Additional digester

Advantage

Faster degradation

Higher methane concentration

Disadvantage

No higher gas yields to be

expected

Mode of actionReduced pH enables enzymes

to work in their optimum Quelle: AAT

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Preacidification

Or dark fermentation

Formation of VFA and alcohols

H2 and CO2

pH value important

Increased enymatic activity

Recirculation

Microbiology

Increasing buffer capacity

H2S formation

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Ultra sound

Principle

Ultra sound into digester

Advantage

Low energy demand

Low investment costs

Disadvantage

No direct degradation of biomass

Mode of actionUS frequences lead to cavity or the

formation of gas bubbles and their

implosionQuelle: ULTRWAVES /D

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Electrocinetical disintegration

Principle

Addition of high voltage impulses

Advantage

Low energy demand

Low investment costs

Disadvantage

No direct degradation of biomass

Mode of actionElectrical field destroyes ionic bounding of

cell walls by changing the chargeQuelle: ATRES Group/D

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Overview influences of the pretreatment

technologies

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Summary/conclusion

Many tests have no reliable data

2 points for BMP tests

Sufficient duration

Pre-treatment technologies specific to substrate

Pre-treatment technologies specific to plant

Awareness of investement and operation costs

Energy balance

Awareness of higher gas yield

Additional effects of pre-treatment technologies

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Thank you

Günther Bochmann

IFA-Tulln Universität für Bodenkultur

Institut für Umweltbiotechnologie

Bioenergy 2020+

Konrad Lorenz Strasse 20

3430 Tulln

[email protected]

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